Islamabad  Pakistan's embattled president, Asif Ali Zardari, is determined to resist pressure to quit, his close aides said Wednesday, after Zardari's sudden hospitalization in Dubai ignited feverish speculation about him resigning.

The president was flown out of the country Tuesday night after what government adviser Mustafa Khokhar described as a minor heart attack. His departure led to runaway rumors that he was about to step down under coercion from the military establishment or even that a coup was in the offing.

The Pakistani president is considered a key ally for Washington in a country that's turned sharply against the post-9/11 partnership with the United States.

Zardari, who's been the president since 2008, is under new stress over allegations that he'd offered Washington a deal to rein in his military in return for American support for his government. Zardari was due to address a special meeting of Parliament over the issue.

The Pakistani president is unpopular at home, polls find, and he's been hounded by the news media, the courts and the military, which are sharply critical.

The government, after first claiming that the president had gone for routine tests, later acknowledged in a statement that he'd sought treatment "following symptoms related to his pre-existing heart condition."

"After the initial medical tests in Dubai, doctors found him to be in stable condition," a statement from the prime minister's office said. "The president will remain under observation and return to resume his normal functions as advised by the doctors."

Rumors about the seriousness of Zardari's condition were compounded by a report on the website of Foreign Policy magazine, which claimed that the Pakistani leader was incoherent while speaking to President Barack Obama on Sunday, when the U.S. president called to offer his condolences over the recent deaths of 24 Pakistani soldiers who were manning a post on the border with Afghanistan when U.S. helicopters accidentally shelled them.

A U.S. official, speaking only on the condition of anonymity because of the sensitivity of the issue, said Zardari was "not focused" during the conversation with Obama.

A close aide to Zardari, who didn't want to be named because he wasn't authorized to speak to the media, said: "He is not a weak man. He doesn't crumble under pressure."

The military has ruled Pakistan for half of the country's history and has exercised power behind the scenes the rest of the time, so it doesn't take much for the nation to become convinced that a coup is imminent.

The military establishment has long sought to remove Zardari, though it appears to want to keep a civilian government in place for now. Diplomatic cables revealed by WikiLeaks indicated that the Pakistani army chief, Gen. Ashfaq Parvez Kayani, had discussed removing Zardari with the then-U.S. ambassador in 2009.

Zardari has a history of heart trouble, and he received treatment for it in London earlier this year.

The president is under extreme pressure from the "memogate" scandal in Pakistan, in which he's accused of being behind a written offer delivered to the U.S. military leadership in the days after Osama bin Laden was killed in an American raid last May. The anonymous memo offered to disband part of the military's notorious spy agency in return for U.S. support. Pakistan's U.S. ambassador and close Zardari aide, Husain Haqqani, has been forced to resign over the issue, and he faces possible treason charges.

There have been loud calls in Pakistan for Obama to apologize for the deaths of the soldiers late last month at the border, but so far the U.S. president has stopped short of doing so. An American military investigation into the controversial incident is ongoing, amid claims from the U.S. side that it was fired on first.